Control valve



Aug. 28, 1945. v E. R'.P|=:CE 2,383,682

. CONTROL vVALVE: Filed Ndv. 28, 1941 gi I w ll f Lm lq N O N I l l Q 1k "'3 j -INVENTOR 5o/Pz PR/ff ATTORNEY PatentedK Aug. 28, 1945 UNITEDSTATES PATENT OFFICE CONTROL VALVE Earl R. Price, South Bend, Ind.,assignor to Bendix Aviation Corporation, South Bend, Ind., a.corporation'of Delaware Application November 2s, 1941, serial No.420,805

1 Claim.

2,353,755 and 2,332,340, respectively, I have disclosed a hydraulicbraking system in which pressure is built up by a combination of manualmeans (using manual in the broad sense) and power or boosterl means. Inthe system disclosed in these applications, pressure created manually ina hydraulic cylinder operates to accomplish Atwo things: iirst to applypressurethrough a series of intermediate parts to brake actuating wheelcylinders or motors and second to operate a valve device which controlsa booster, which in turn adds its effort to the manual force in creatingapplying pressure in the wheel cylinders. Both of my earlierapplications have included in the brake applying-,systems disclosedmeans for exerting a reaction against the manually applied economicalthan any other comparative system. In this connection,'it may b e notedthat I have eliminated entirely'the use of an independent diaphragm vrother reaction sensitive means which must be used whenever reactiondepends upon the amount of power exerted by a differential air pressurepower unit.

Other objects and features of my invention will be apparent during thecourse ofthe followforce to indicate to the operator the extent of powerwhich is being applied to operate the brakes. In my earlierapplicationsthe reaction or feel is provided within the valve device whichcontrolsthe booster, and the amount or strength of the reaction depends upon thepower which is being utilized to aid in applying the brakes.

It is the object of this invention to provide, in a braking system ofthe same general type referred to in the earlier applications, Aa meansfor exerting reaction in which,l the amount of reaction will depend uponthe pressure in the hydraulic iiuid at the wheel cylinders rather `thanthe power which is being used to create pressure in the hydraulic iluid.v

In line with the above I have provided a combined manual and powersystem for operating hydraulic brakes in which reaction or feel dependeupon the pressure of, the hydraulic liquid applications with a systemwhich may be more ing description, reference being had to theaccompanying drawing, in which:

Figure 1 is a generally diagrammatical illustration of a hydraulic brake'operating system embodying my invention, with the control and reactionvalve whichis the center of theinvention shown in vertical section.

The operation of the system illustrated in Figure 1 generally comparesto that of the systems disclosed in either of my earlier applicationsreferred to above. Generally, it comprises a pedal operated mastercylinder l I, a pedal l2, a controlvalve i3 connected by a conduit id tothe master cylinder l i, an auxiliary or booster operated mastercylinder i5 connected by a conduit it with the master cylinder ll and bya conduit l'i with a wheel or motor cylinder i8 which is adapted tooperate a brake i9 in the customary( manner. The auxiliary cylinder l5is adapted to be operated in part by a differential air' pressurebooster or power unit 20 which has 'one side connected by .a diierentialair pressure line 2l to the valve i3 I and has its other side connectedby a vacuum line 22 to the intake manifold, which is the usual source ofvacuum.' A branch 'vacuum line 23 connects the intake manifoldY to thecontrol valve it. Of particular importance in this application is ahydraulic conduit 2d which connects the conduit il to the control valvei3.

The control valve i3 formsv two opposing hydraulic chambers 25 and 26,in which are reciprocable pistons 2l and 28 respectively. The controlvalve I3 also has a. central chamber 29 and three ports 30, 3l and 32opening into the chamber 29.

'I'he port 30 connects the chamber 29 by meansv of line 2l with one sideof the booster 20. Ports 3l and 32 are controlled respectively by valveelements $3 and 3, which are preferably of the poppet type. When valveelement 33 is moved to open port 3l it connects chamber 29 throughconduit 23 with the system 'of suction; when-valve element 34 opens port32 it connects chamber 2 9 with the atmosphere. A valve control member35 which may comprise a rod or bar, is shown connected at opposite ends.5to the valve elements 33 andV 3- and is positioned between the pistons21 and 28 with the said pistons bearing against the rod 35 so thatreciprocating movement of the pistons moves the rod 35 to open and closethe suction and atmosphere ports 3| and 32.

Operation of the system is generally the same as that o1' the systemsshown in my prior applications referred to above with the exception ofthe control valve I3. Manipulation of the pedal l2 places underpressurefluid in the cylinder II and the pressure is exerted in twoways: rst, through the auxiliary cylinder I5, to actuate the motor I 8and, second, through the piston 21 in control valve I3, to move the rodor bar 35 to rst close the vacuum or suction port lll` and subsequentlyopen the atmosphere port 32 to admit air underA .the operation of thebooster and auxiliary cylinder in my priorapplications referred toabove. The manually produced pressure and the booster produced pressurenow combine to build up pressure on the hydraulic iluid in the conduitI1 and the motor I8, applying the brake I8.

The pressure in conduit I1 is transmitted 'through conduit'24 to theliquid in chamber 28 -of control valve I3 and pressure is thereforeexerted against the piston 28 in accordance with the pressure prevailingin conduit I1. This pressure exerted against piston 2B tends to resistthe l movement of piston 21 and in resisting said movejmosphere port32.-

ment tends to return the control valve I3v to lapped position'.pressures on the pistons 21 and 28 will depend on the cross sectionalareas` of the pistons and onthe unit pressures prevailing in thechambers 25 and 28. When the unit pressure in chamber 28 is suillcientto move the smaller piston 28 against the larger piston 21, the controlmember or rod- 35 will be moved upward to close the atport 3'2 andvacuum port 3| closed as shown in Obviously the total opposed the gure,control valve I3 isin lapped position, and no further booster pressurewill be exerted on the brakes until increased manual pressure is exertedon the fluid in cylinder II. Thus, the brake applying system describedis pressure responsive, i. e., the operator is enabled to judge from--the feel" of the pedal the amount of pressure which is being exerted toapply the brakes. When it is desired to release the brakes, pedal I2 maybe released to lower the pressure in cylinder II, with the result thatthe pressure against piston 28 overcomes the pressure against piston 21and reopens vacuum port 3l to connect line 2| to vacuum and establish abalance in the booster 28, suspending the booster piston in vacuum. Atthe same time the hydraulic iluid in the systei'n is returned under theiniluence of following claim.

I claim: y,

For use in a hydraulic system having a primary hydraulic pressure anda'secondary hydraulic pressure, a, control valve structure having twocoaxial differential diameter bores, a piston in each of said bores, onesubjected to the primary pressure and the other subjected to thesecondary pressure, said pistons being independently reciprocable intheir bores vand being urged by hydraulic pressure toward one another,said control valve structure having an atmosphereport' and a vacuumport, poppet valve elements for With both the atmosphere controlling theopening and closing of said ports, and a floating beam pivoted at oneend to one of the poppet valve elements and at the other end

